The present invention relates to a thigh prosthesis or artificial leg designed to permit instinctive movements that amputees to whom a thigh has been amputated should effect to be able to keep in balance on the artificial leg and to walk.
An amputee to whom a thigh has been amputated is generally given an artificial leg or thigh prosthesis designed to be of the same length as his non-amputated leg. Such a prosthesis is often unsatisfactory as it is suitable to ensure only static balance. To obtain safe dynamic balance a thigh prosthesis sensitive to motion variations would be required.
Thigh prosthesis of the prior art are found to be quite cumbersome to use and difficult and expensive to manufacture. Some conventional artificial legs are also provided with braking devices to prevent the user from falling. However, braking devices are generally useless as they exert positive action only when the user has already lost his balance.
Furthermore, prior art artificial legs are designed to shorten during advance movement of the user's non-amputated leg (active deambulation phase), which results in the amputee's center of gravity being considerably lowered. Thus, in the following deambulation passive phase (i.e. when the artificial leg is lifted by the user to allow it to lengthen) the user must effect a considerable additional effort to raise his own center of gravity.
The most relevant prior art known to the applicant is: U.S. Pat. Nos. 3,901,223 and 4,145,766.